Bed tramming with dual z motors but no probe

Gradually upgrading my v2 to v2.5 and I have made the switch to using dual z motors with integrated tr8x8 leadscrews. I now have two z endstops and adjustment screws on my build plate supports to adjust endstops trigger point.

I have not yet upgraded the carriage to support a BLtouch as that involves printing a new carriage and probably getting new bushings.

Question is, what’s the best way to go about tramming the bed now that I have these two independent motors and endstops?

Best guess so far is to bring the carriage to one side near the screw and bring it up to the nozzle and get the gap down to 0.1mm through manual jogging and then adjust the endstops trigger point till it just about triggers, then repeat for the other side? Any better techniques anyone has come up with?

I think you can do it with software offsets on the end stops so you don’t have to be tweaking the screws. I do mine with a BL touch of course but I think if you just enable the dual independent z in Marlin, it has some comments about how to enable automatic tramming.

Hmm yeah I setup the dual z endstops setting in the config. Unfortunately it seems to just ignore it.

Running m119 I can see both z_min and z2_min are triggering when I depress the switches. And they’re within a mm of each other in terms of trigger points.

But when I do home it more often than not just ignores one of the switches and continues to seek past the end of the stop.

Could be more noise in the system I guess from having two motors? Or could just be that I’m still using a shonky 1.0b smoothieboard with marlin 2 and there’s just some timing bug. The smoothievoard doesn’t have interrupt driven min/max pins so I’m guessing it could likely be a firmware issue.

I have an skr 1.4 turbo to drop in which should also give me quieter steppers so I guess I’ll make that change next and see if it helps.

Got the skr 1.4 turbo setup today. Oh my God the tmc2209 are a huge upgrade from the a4498 on the old smoothieboard. So much quieter and smoother!

It also fixed the dual z homing issue I was having. Overall a totally worthwhile upgrade.


Yeah it’s really surprising how much value you get for the money with the SKR boards. I feel bad because I’ve always been really loyal to Roy and Panucatt Devices,
he has taken good care of me over the years and always been a good friend. But it’s hard to discount the value you get with the BTT equipment. And they’re actually pretty good about posting source and information out on their GitHub. I’m glad you got it working, and yeah the 2209’s really are an excellent driver. I’ve had mixed results with hybrid threshold, but other than that they really are great.

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